External Directives

You can use the SAVE EXTERNAL DIRECTIVES statement to store optimizer directives in the sysdirectives table of the system catalog. Informix® applies these external directives automatically to subsequent queries and subqueries that match a specified SELECT statement.

The EXT_DIRECTIVES configuration parameter and the IFX_EXTDIRECTIVES environment variable can be set to control whether external directives are enabled or disabled for the database server instance or for the session. Setting either of these to zero disables external directives; setting both to 1 enables external directives.

You can also use the EXTDIRECTIVES option of the SET ENVIRONMENT statement to enable or disable external directives during a session. For more information, see Enabling or disabling external directives for a session.


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